"This effort started with the release of Skype 6.0 for Mac and Windows a few weeks ago, which allows you to sign into Skype using a Microsoft account. Now Messenger users just need to update to the latest version of Skype, sign in using a Microsoft account, and their Messenger contacts will be there."

He promises broader device support for all platforms, including iPad and Android tablets, along with instant messaging, screen sharing, the ability to call landlines and video calling, including group calls.

The speed of the transition has taken some by surprise, and many users are concerned. Some features, such as 'nudge', remote assistance and games look like they'll no longer be available.

There's always the danger that some users will switch to another service instead, such as WhatsApp Messenger or Google Talk. If everbody moves over, though, the merger will boost Skype's users by a third.